package Day2025_03_12;

public class LeetCode0801 {
    public int waysToStep(int n) {
        if (n == 1) return 1;
        if (n == 2) return 2;
        if (n == 3) return 4;
        int[] dp = new int[n + 1];
        dp[1] = 1; dp[2] = 2; dp[3] = 4;
        for (int i = 4; i <= n; i++) dp[i] = ((dp[i - 1] + dp[i - 2]) % 1000000007 + dp[i - 3]) % 1000000007;
        return dp[n];
    }
}
